Study On The Composite Foundation Improved By Flexible Piles Under Flexible Foundation Basis On The Damage Soil Mechanics

Composite foundation has become one of important foundation which often be used in Civil Engineering. However, the theory of all kinds of composite foundation is imperfect, and the theory lags of the development of practice. So there is much possible to advance and create in this field. Through the analysis of difference between the stiff foundation and flexible foundation, this article emphasizes the imperfect in theory and in practice about the composite foundation under the load of flexible foundation when people utilize the theory of composite foundation under the load of stiff foundation. Basis on the analysis this article aim to create new thinking to reason the character of composite foundation through combine the tradition soil mechanics with the damage mechanics. It creates the soil damage concept and definition basis on the analysis of soil three phrases construct. And consider the earth framework distortion is the soil damage distortion. Study the relationship of soil stress-strain from the microcosmic and macroscopic, conceder there is not only elastic distortion, plastic distortion but also the damage distortion during the process of soil accept the load. For the minor consolidate soil and normal consolidate soil the damage distortion exist in entire process, for the super consolidate it should make sure the initial damage thresholds firstly.Based on the damage mechanics, this article study the character of composite foundation improved by flexible piles under flexible foundation. It divides the settlement of reinforce field to two parts: piles settlement and soil settlement according to force balance. Furthermore, it consider the pile settlement consist of elastic distortion, plastic distortion and the damage distortion. Under the load of flexible foundation for long time, the piles would pierce in two sides relate to soil among the piles because of the big difference about the module of piles and soil. In fact, the distortion of pierce would happen many times on the bottom of piles and this pierce distortion would set free some elastic distortion, on the other hand hold the damage distortion and the plastic distortion forever. For the settlement of reinforce field, this article create the compute model bases on the main reason of pile damage distortion;For thesettlement of underlying soil layer of composite foundation, this article combine the damage theory and the traditional measure through analyze the damage distortion which be considered the earth framework distortion.We can make the best of this new thinking to explain the complicacy and diversity of soil distortion when this article introduces the damage mechanics to traditional soil mechanics. It builds the relationship between the earth distortion in microcosmic character and the soil settlement in macrocosmic character through the compute model. At last, it proved that the result come from the compute model embody the finally distortion of composite foundation through the engineering practice.